Machine-switching telephone-exchange system.



B. G. DUNHAM.

MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT- I4| 19l5.

Patented Jan. 2, 191?.

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BERT

MENTS, TO WESTERN ELECTRIC GGMPANY,

NEW YORK.

Gr. DUNHAM, 0F HAWTHORNE, NEW JERSEY, ASSIGNOR, BY

MESNE ASSIGN- INCORPORATED, A CORPORATION OF Specification of Letters Patent.

Patented Jan. 2, 191?.

Application filed September 14, 1915. Serial No. 50,589.

To all whom it may concern I Be it known that I, BERT G. DUNHAM, a citizen of the United States, residing at Hawthorne, in the county of 'Passaic an State of New Jersey, have invented certain new and useful Improvements in Machine- Switching Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing machine switching and its object is to provide an improved connector circuit.

One of the features consists in a simple circuit arrangement wherein, upon the termination of units selection the secondary steppmg magnet is removed from the control of the calling party. This is brought about by so arranging the circuit that the side switch 7 moves out of the testing position when the last units impulse is sent, whether the selected line is busy or idle, and consequently the connection between the said magnet and the stepping relay contact is opene since it includes one of the side switch arms. However, after the connector test brush engages the test contact of the line. selected, and before the side switch advances a relay connected to the test brush is operated and locked up if the line is busy. vanced position of the side switch, due to the operated condition of this relay, a busy back apparatus is connected to the calling line. If, on the other hand, the selected line is idle, this relay remains inert, and in the advanced position of the side switch this inert condition renders operative means to connect a ringing generator with the selected line, and to prevent the connection of the busy back apparatus with the calling line.

The invention will be more readily understood when described with reference to the accompanying drawing.

For simplicity the connector circuit only is shown, it being understood that .a connection would ordinarily lead from the calling substation A through one or more finde'rs and group selectors, the connector shown, to the called substation B. lVhen the calling line has been ex tended through to the connector, therefore,

contact of relay 10,

In the ad- I and finally through" the relay 1O thereat is energized over the following circuit: free pole of battery, right winding of relay 10, conductors 11, 12, selector terminal 13, selector brush 14, conductor 15, finder brush 16, finder terminal 17, line conductor a through the telephonic apparatus at substation A, sender S, line conductor 5, finder terminals 18, brush 19, conductor 20, selector brush 21, selector terminal 22, conductors 23, 24, left winding of relay 10, to ground. Relay 10 at its armature and front contact closes thefollowing circuit for a relay 25: free pole of battery, relay 25, conductor 81, armature and front to ground. Relay 25 at its armature and back contact interposes a break in the circuit of release magnet 80. Relay 25, being slow, remains energized while the sender S is interrupting the line circuit in transmitting the tens and units digits of the called line. Relay 10 at its armature and front contact also closes the following circuit to energize a slow relay 26: free pole of battery, relay 26, conductor 27 side-switch arm l and its first contact conductor 28, primary off-normal contact 29, conductors 30,81, armature and front contact of relay 10, to ground. Relay 26 at its left armature and front contact closes the following circuit for the magnet 35, which is the escapement magnet of the sideswitch: free pole of battery, magnet 35, conductor 36, left armature and front contact of relay 26, conductor 37, right armature and back contact of relay 38, conductor 39, side-switch arm 5 and its first contact, to ground. The calling party at substation A now operates the sender S, to control tens selection, which sender, in the well-known manner, interrupts the line circuit. Each time the armature of relay 10 closes its back contact, the following circuit is closed to drive the brush shaft (not shown), carrying the brushes 45, 16, 47 in a primary direction, into operative .relation to the group of lines containing the wanted line: free pole of battery, primary magnet 31, conductor 32, side-switch arm 6 and its first contact, conductor 33, armature and front contact of relay 25, conductor 34:, armature and back contact of relay 10, to ground. Upon the first step of the shaft, the priz that ary stepping magnet 43:

mary off-normal spring 29 opens its upper contact and closes its lower contact. Consequently when the sender S restores and maintains the relay 10 energized," the relay 26 becomes denergized, and at its leftarmature and front contact opens the circuit of side-switch escapement magnet 35, and arranged to release the well-known manner.

In position 2, side-switch arm 4 closes the following circuit for relay 26: free pole of battery, relay 26, conductor 27, sideswitch arm 4 and its second contact, conductor 40, secondary oft-normal spring 41 and its upper contact, conductors 42, 30, 81, armature and front contact of relay 10, to ground. Relay 26 again at its left armature and front contact closes the circuit of side- 'switch magnet 35, this circuit being the same as'that previously traced with the exception the side-switch arm 5 is now in engagement with its second contact. The calling party now operates his sender S to transmit the units digit of the wanted line. Each time the line relay l0 closes its back contact, the following circuit is closed for the second free pole of bat tery, magnet 43,, conductor 44, side-switch arm 6 and itssecond contact, conductor 33 armature and front contact of relay 25, conductor 34, armature and back contact of relay 10, to ground. Upon the first secondary step of the selector, the secondary olfnormal spring 41 is transferred to its lower contact. When the last units impulse is transmitted, if the line selected, represented by the multiple terminals 48, 49, 50 with which brushes 45, 46, 47 are then in contact, is busy, the following circuit is closed: free pole of battery, right winding of relay 51, conductors 52, 53, 54, side-switch arm 3 and its second contact, test brush 47, to grounded test terminal 50. Since the circuit for slow relay 26 leads through the armature and back contact of relay 10, the relay 26 after an interval retracts its armatures. When the left armature closes its back con tact, relay 51 looks itself over the following circuit: free pole of ture and front contact of relay 51, conductor 55, left armature and back contactof relay 26, conductor 37, right armature and back contact of relay 38, conductor 39, side-switch arm 5 andvits second contact, to ground. Relay 26 in denergizing allows magnet 35 to deenergize to release the side-switch into position 3. The circuit traced, including the left armature and back contact of relay 26, isclosed before the side-switch is released into position 3. The escapement magnet 35 at its left armature and back contact applied busy tone to line conductor 23 over side switch arm :9 and its third contact, and thus battery, right wind ing of relay 51, conductors 52, 53, left arma 43 from the calling party. When the calling party hangs up his receiver, the circuit of relay 25 is opened at the armature and front contact of relay 10. After an interval, relay 25 retracts its armature, whereupon the following circuit is closed for release magnet 80: free pole ofbattery, magnet 80, conductor 57, primary off-normal spring 58, conductor 59, side switch arm 7 and its third contact, conductor 60, armature and back contact of relay 25,'conductor 34, armature and back contact ofrelayv 10, to ground. Therelease magnet 80 restores the connector and side-switch in thewellknown manner, and locksitself in a circuit controlled at primary off-normal spring 58. When the connector completely restores, off normal spring 58 opens, whereupon the release magnet retracts its armatures thus opening the locking circuit. The deenergization of relays 10 and 25 grounds conductor 61. As side-switch arm position 1, this ground is extended back to the selectors and finder to release the same in the well-known manner. If the selected line is idle, test terminal 50 is not grounded. Consequently, relay 51 is not energized when connection is made to the wanted line, and when the side-switch moves into position 3, upon the deenergization of relay 35 the following circuit is closed to again energize re lay 26: free pole of battery, relay 26, con- 8 is now in.

ductor, 27 side-switch arm 4' and its third contact, conductor 90, right armature and back contact of relay 51, to ground. Ground is applied to thev'multiple test terminal 50 to cause the seized line to test busy to other testing connectors or finders as follows: ground, right armature and back contact of relay 51, conductor v90, right armature and front contact of relay 26, conductor 75, arm 3, brush 47 to multiples 50 of the selected line. Magnet 35 is energized over the following circuit upon the energizationof relay 26 to apply ringing current to the select brush 46, terminal 49, line conductor a, bell 65, condenser 66, sender S7, line conductor 5, terminal 48, brush 45, side-switch arm 1 and its third contact, conductors 67, 68, left armature and front contact of magnet 35, conductor 69, to ground. 7

When the party at substation B removes his receiver, the relay 38, which is marginal, responds in the well-known manner. This relay at its armature and back contact opens the circuit of escapement magnet 35, which magnet in retracting its armatures opens the ringing circuit and releases the side-switch into position 4:. In position 4, the called supervisory relay 51 is energized over the following circuit: free pole of battery, right winding of relay 51, conductors 52, 58, sideswitch arm 2 and its fourth contact, brush 46, terminal 49, line conductor a, through the telephonic apparatus at substation B, conductor Z), terminal 48, brush L5, sideswitch arm 1 and its fourth contact, conductors 70, 71, left winding of relay 51, to ground. Relay 51 at its right armature and front contact closes the following circuit for relay 26: free pole of battery, relay 26, conductor 27, side-switch arm 1 and its fourth contact, conductor 72, right armature and front contact of relay 51, to ground. Upon the release of the side-switch into position 4, ground is applied to the multiples 50 over side-switch arm 3. Talking current is supplied to the called party over the windings of relay 51 and to the calling party over the windings of relay 10. Upon the termination of the conversation, the replacement of the receiver by the called party opens the circuit of relay 51, which at its right armature and front contact opens the circuit of relay 26.

This relay after an interval retracts its arma tures, closing the following circuit for the release magnet free pole of battery, release magnet 80, conductor 57, primary offnormal spring 58, conductor 59, arm 7 and its fourth contact, conductor 73, right armature and back contact of relay 26, conductor 90, right armature and back contact of relay 51, to ground. Magnet 80 at its left armature and front contact locks itself in a circuit controlled by the primary off-normal spring 58. Consequently, when the connector restores and this spring opens, the release magnet is deenergized. The release magnet in energizing restores the side-switch in the well-known manner. When the calling party hangs up his receiver, the relay 10 is deenergized. This relay in deenergizing opens the circuit of relay 25, which after an interval retracts its armature, thereupon grounding conductor 61 which leads back over side-switch arm 8 to the preceding selectors and finder, thus releasing the same. If the calling subscriber abandons the call before the called party answers, the following circuit is closed to restore the connector and side switch: free pole of battery, magnet 80, conductor 57, primary off-normal spring 58, conductor 59, arm 7 and its first, second or third contacts, conductors 61, 60, armature and back contact of relay 25, conductor 34, armature and back contact of relay 10 to ground. Arm 8 extends this ground back to the preceding switches to release the same.

What is claimed is:

1. In a telephone exchange system, the combination with an automatic selector switch, lines terminating therein, means for setting said switch on said lines, and a sideswitch controlling said automatic switch, of a relay associated with said automatic switch, means for operating the same or not according to the condition of the selected line, said relay when operated being adapted to lock itself up, means for advancing the side-switch when connection is made with a selected line irrespective of the condition of such line, a generator, a busy,

back apparatus, and means controlled by said relay and adapted when the side-switch is advanced to connect said generator with the selected line or said busy back apparatus with the calling line, dependent upon the condition of said relay.

2. In a telephone exchange system, the combination with an automatic selector switch, lines terminating therein, means for setting said switch on said lines and a sideswitch controlling said automatic switch, of a relay associated with said automatic switch, means for operating the same or not according to the condition of the selected line, said relay when operated being adapted to lock itself up, means for advancing the side-switch when connection is made with a selected line irrespective of the condition of such line, a generator, a busy back apparatus, a magnet controlled by said relay and adapted when said side-switch is advanced to apply ringing current to the selected line or to connect said busy-back apparatus with the calling line, dependent upon the condition of said relay.

3. In a telephone exchange system, the combination with an automatic selector switch, lines terminating therein, a stepping relay, a stepping magnet controlled thereby for setting said switch on said lines, a sender controlling said stepping relay, a side-switch controlling said automatic switch, an arm of said side-switch being adapted to connect said magnet to a contact of said stepping relay, of a relay associated with said automatic switch, means for operating the same or not according to the busy or idle condition of the selected line, said relay when operated being adapted to lock itself up, means for advancing said sideswitch arm to disconnect said magnet from said stepping relay contact irrespective of the condition of the selected line, a generator, a busy back apparatus, and means controlled by said relay and adapted when the side switch is advanced to connect said generator with the selected line or said busy back apparatus with the calling line,

dependent upon the condition of said relay. v

4. In a telephone exchange system, the combination with an automatic selector switch having a test brush, lines terminating in said switch, multiple test terminals therefor, a stepping relay, a stepping magnet controlled thereby for setting said switch on said lines, means for grounding the test terminals of busyv lines, a sender controlling said stepping relay, a side-switch controlling said automatic switch, and an arm of said side-switch being adapted to connect said magnet to acontact of said stepping relay, of a relay associated with said automatic switch, a circuit for said relay adapted to be closed when said test brush engages .the test terminal of a busy selectedline, a

locking circuit for said relay, means for advancing said side-switch arm to disconnect said magnet from said stepping relay contact irrespective of the condition of the selected line, a generator, a busy-back apparatus, and means controlled by said relay and adapted when the-said switch is advanced to connect said busy-back apparatus with the calling line or said generator with the selected line, depending upon the condition of said relay. 7

5. In a telephone exchange system, the combination with an automatic switch hav- 'ing a test brush, lines terminating therein, test terminals therefor, means for setting said switch on said lines, means for grounding the test terminals of busy lines, a sideswitch controlling said automatic switch, a ringing generator, a busy-back apparatus, and a release circuit for said automatic switch, of a relay 51 connectedto said test brush, a circuit for said rela-y'adapted to be closed when said test brush engages the test terminal of a busy selected line, a locking circuit for said relay, means for advancing the side-switch when connection is made with a selected line irrespective of the condition of such. line, a slow relay 26 adapted in such advanced position to be'operated if relay 51 remains inert and controlling at its armature and back contact said release circuit,

a relay adapted to be operated by the energization of said relay 26, said relay 35 being adapted when energized to apply current from said generator to the selected line, means for advancing the side-switch into the talking position upon the response of the called party and for including'said relay 51 in circuit with the called line, and a circuit for said relay 26 controlled by said relay 51 in such position.

In witness whereof I hereunto subscribe my name this 1st day of Sept, A.'D. 1915.

BERT G. DUNHAM.

Copies of this patent may be obtained for five cents each, by addressingtl e Commissioner of Patents,

Washington, D. O. 

